Hi Marcusm and thank your for your interest.

Decoupling capacitor prevent Midi unwanted error (http://en.wikipedia.org/wiki/Decoupling_capacitor). They are wired between power and ground.

I thought that I had sensitive problems but in fact, i wrote to the Highly Liquid conceptor and he tell me to add the decoupling capacitor close to each pot. I had to footswitch for prevent (i ve seen some on new Marshall footswitches). I also think that I could have less problem with better pots.

Hope I have been helpfull :).